The present invention relates generally to improvements in the production molded assemblies and it relates particularly to an improved method and apparatus for the production of mutually thread engageable members or assemblies.
Hitherto, it has been a common practice in the manufacture of two thread engageable members to mold or manufacture the members separately. However, such a pair of thread engageable members are generally mismatched and possess non-compensating errors by reason of their independent fabrication, since it is generally impossible to manufacture such threaded members in true conformity with design dimensions. This then leads to a loose coupling and hence a lack of smooth operation between the two thread engaged members, because of the accumulation of errors which have been independently incurred.
In addition, where these two thread coupled members are manufactured separately, such as for instance, in the case of a focusing ring and a lens holding frame in the lens barrel of a camera which are to be used in mutual engagement with each other, there arises the need to assemble the two members for adjustment for correct engagement, after the manufacture of both members. This dictates an expenditure of much time and effort throughout a period from the manufacture to the assembly. Moreover, the finer the threads, the more difficult it is to complete the proper alignment of an axis of one thread with that of the other. A high degree of skill is required for the adjustment of the threads, resulting in an increased number of unacceptable and rejected parts if such operation is performed by operators with little experience.
Furthermore, in accordance with the aforesaid process of manufacturing the both members separately, quality control must be conducted for the male-threaded parts and the female-threaded parts in cooperation with each other, and hence the complexity in manufacture and assembly is increased with an increase in the number and type of parts, with an accompanying increase in the man hours consumed in control operations as well as an increase in manufacturing cost.